This grant application proposes to further develop and evaluate an extracorporeal membrane oxygenator based on transmembrane catalysis of H2O2. This device achieves respiratory gas exchange by transporting across a hemodialysis membrane highly water soluble derivatives of the respiratory gases, namely hydrogen peroxide and bicarbonate ion. The associated accumulation in the blood of buffered hydrogen ion is neutralized by absorption of hydroxyl ion from the dialysis bath. Oxygen transfer in this device is not limited by diffusion across the blood-membrane boundary layer as in other membrane oxygenators. Instead O2 transfer is a function of the concentration of H2O2 in the dialysis bath. The oxygen produced on the surface of the catalyst impregnated membrane is evenly distributed over the membrane surface. To take advantage of the potent oxygenation which can be produced (up to 900 ml/min/M2), an oxygenator with high blood flow rate and rapid mixing has been designed, built and evaluated. The design is based on the rotating disc principle. Further effort is being directed at increasing the useful life of the membrane catalyst beyond its present duration of 4 hours, and in scaling up the design of the oxygenator to accommodate an adult size patient. The catalyst-membrane oxygenator offers the advantage of simultaneous artificial kidney treatment. The device may also be useful in maintaining acid-base balance and in correcting edema states by ultrafiltration. This type of membrane oxygenator uses hydrophilic rather than hydrophobic membranes which may prove to be more biocompatible.